src/msw/textmeasure.cpp

   1 ///////////////////////////////////////////////////////////////////////////////
   2 // Name:        src/msw/textmeasure.cpp
   3 // Purpose:     wxTextMeasure implementation for wxMSW
   4 // Author:      Manuel Martin
   5 // Created:     2012-10-05
   6 // RCS-ID:      $Id:
   7 // Copyright:   (c) 1997-2012 wxWidgets team
   8 // Licence:     wxWindows licence
   9 ///////////////////////////////////////////////////////////////////////////////
  10
  11 // ============================================================================
  12 // declarations
  13 // ============================================================================
  14
  15 // ----------------------------------------------------------------------------
  16 // headers
  17 // ----------------------------------------------------------------------------
  18
  19 // for compilers that support precompilation, includes "wx.h".
  20 #include "wx/wxprec.h"
  21
  22 #ifdef __BORLANDC__
  23     #pragma hdrstop
  24 #endif
  25
  26 #include "wx/msw/private.h"
  27
  28 #ifndef WX_PRECOMP
  29     #include "wx/window.h"
  30     #include "wx/font.h"
  31 #endif //WX_PRECOMP
  32
  33 #include "wx/private/textmeasure.h"
  34
  35 #include "wx/msw/dc.h"
  36
  37 // ============================================================================
  38 // wxTextMeasure implementation
  39 // ============================================================================
  40
  41 void wxTextMeasure::Init()
  42 {
  43     m_hdc = NULL;
  44     m_hfontOld = NULL;
  45
  46     if ( m_dc )
  47     {
  48         wxClassInfo* const ci = m_dc->GetImpl()->GetClassInfo();
  49
  50         if ( ci->IsKindOf(wxCLASSINFO(wxMSWDCImpl)))
  51         {
  52             m_useDCImpl = false;
  53         }
  54     }
  55 }
  56
  57 void wxTextMeasure::BeginMeasuring()
  58 {
  59     if ( m_dc )
  60     {
  61         m_hdc = m_dc->GetHDC();
  62
  63         // Non-native wxDC subclasses should override their DoGetTextExtent()
  64         // and other methods.
  65         wxASSERT_MSG( m_hdc, wxS("Must not be used with non-native wxDCs") );
  66     }
  67     else if ( m_win )
  68     {
  69         m_hdc = ::GetDC(GetHwndOf(m_win));
  70     }
  71
  72     // We need to set the font if it's explicitly specified, of course, but
  73     // also if we're associated with a window because the window HDC created
  74     // above has the default font selected into it and not the font of the
  75     // window.
  76     if ( m_font || m_win )
  77         m_hfontOld = (HFONT)::SelectObject(m_hdc, GetHfontOf(GetFont()));
  78 }
  79
  80 void wxTextMeasure::EndMeasuring()
  81 {
  82     if ( m_hfontOld )
  83     {
  84         ::SelectObject(m_hdc, m_hfontOld);
  85         m_hfontOld = NULL;
  86     }
  87
  88     if ( m_win )
  89         ::ReleaseDC(GetHwndOf(m_win), m_hdc);
  90     //else: our HDC belongs to m_dc, don't touch it
  91
  92     m_hdc = NULL;
  93 }
  94
  95 // Notice we don't check here the font. It is supposed to be OK before the call.
  96 void wxTextMeasure::DoGetTextExtent(const wxString& string,
  97                                        wxCoord *width,
  98                                        wxCoord *height,
  99                                        wxCoord *descent,
 100                                        wxCoord *externalLeading)
 101 {
 102     SIZE sizeRect;
 103     const size_t len = string.length();
 104     if ( !::GetTextExtentPoint32(m_hdc, string.t_str(), len, &sizeRect) )
 105     {
 106         wxLogLastError(wxT("GetTextExtentPoint32()"));
 107     }
 108
 109 #if !defined(_WIN32_WCE) || (_WIN32_WCE >= 400)
 110     // the result computed by GetTextExtentPoint32() may be too small as it
 111     // accounts for under/overhang of the first/last character while we want
 112     // just the bounding rect for this string so adjust the width as needed
 113     // (using API not available in 2002 SDKs of WinCE)
 114     if ( len > 0 )
 115     {
 116         ABC widthABC;
 117         const wxChar chFirst = *string.begin();
 118         if ( ::GetCharABCWidths(m_hdc, chFirst, chFirst, &widthABC) )
 119         {
 120             if ( widthABC.abcA < 0 )
 121                 sizeRect.cx -= widthABC.abcA;
 122
 123             if ( len > 1 )
 124             {
 125                 const wxChar chLast = *string.rbegin();
 126                 ::GetCharABCWidths(m_hdc, chLast, chLast, &widthABC);
 127             }
 128             //else: we already have the width of the last character
 129
 130             if ( widthABC.abcC < 0 )
 131                 sizeRect.cx -= widthABC.abcC;
 132         }
 133         //else: GetCharABCWidths() failed, not a TrueType font?
 134     }
 135 #endif // !defined(_WIN32_WCE) || (_WIN32_WCE >= 400)
 136
 137     *width = sizeRect.cx;
 138     *height = sizeRect.cy;
 139
 140     if ( descent || externalLeading )
 141     {
 142         TEXTMETRIC tm;
 143         ::GetTextMetrics(m_hdc, &tm);
 144         if ( descent )
 145             *descent = tm.tmDescent;
 146         if ( externalLeading )
 147             *externalLeading = tm.tmExternalLeading;
 148     }
 149 }
 150
 151 bool wxTextMeasure::DoGetPartialTextExtents(const wxString& text,
 152                                             wxArrayInt& widths,
 153                                             double scaleX)
 154 {
 155     if ( !m_hdc )
 156         return wxTextMeasureBase::DoGetPartialTextExtents(text, widths, scaleX);
 157
 158     static int maxLenText = -1;
 159     static int maxWidth = -1;
 160
 161     if (maxLenText == -1)
 162     {
 163         // Win9x and WinNT+ have different limits
 164         int version = wxGetOsVersion();
 165         maxLenText = version == wxOS_WINDOWS_NT ? 65535 : 8192;
 166         maxWidth =   version == wxOS_WINDOWS_NT ? INT_MAX : 32767;
 167     }
 168
 169     int len = text.length();
 170     if ( len > maxLenText )
 171         len = maxLenText;
 172
 173     int fit = 0;
 174     SIZE sz = {0,0};
 175     if ( !::GetTextExtentExPoint(m_hdc,
 176                                  text.t_str(), // string to check
 177                                  len,
 178                                  maxWidth,
 179                                  &fit,         // [out] count of chars
 180                                                // that will fit
 181                                  &widths[0],   // array to fill
 182                                  &sz) )
 183     {
 184         wxLogLastError(wxT("GetTextExtentExPoint"));
 185
 186         return false;
 187     }
 188
 189     return true;
 190 }